Process for producing titanium enriched slag



Sept. 9, 1958 P. TARDIEU PROCESS FOR PRODUCING TITANIUM ENRICHED SLAGFiled oct. 51, 195e INVENTOR 'Pierre Tardieu.

ATTORNEY United States PROCESS FOR PRGDUCING TITANIUM ENRICHED SLAGPierre Tardieu, Edea, Cameroons, assignor to Pechiney,

Compagnie de Produits Chimiques et Eiectromeailurgiques, Paris, France,a corporation of France Application @ctoncr 31, 1956, Serial No. 627,718

Claims priority, application France November 10, 1955 is Claims. (c1.75-30) The present invention, which results from applicantsinvestigations, concerns a new process for enriching ores containingtitanium oxide with this compound. It relates more particularly to thetreatment of ores such as ilmenite and rutile. The invention alsorelates to apparatus adapted for carrying out the new process.

A known method, currently use d for enrichment (concentration) ofilmenite, consists in reducing the iron oxides contained therein and,thereafter, separating the iron from the titanium oxide-containing slag.

The reduction is generally carried out with coal r coke which is reactedat temperatures up to 1700" C.;

Jthe formed cast iron is separated in the liquid state and,

more often than not, the slag is liqueed by means of various uxes. Forexample, a known process consists in carrying out this invention in anelectric furnace. However, the known processes do not make it possibleto obtain slags which are very rich in Ti02; there always remains in theslag a considerable proportion of iron oxide, iluxes, or oxides such asmagnesia, lime, silica, alumina, etc.

In contrast with the foregoing, the present invention makes it possibleto increase the concentrationV of titanium oxide to a very high degree,generally well above 75%, under economical conditions and, moreover, itenables, if necessary, to obtain a product which is free from CaO, MgO,A1203 and Si02, or a product which contains only very low proportions ofthese impurities.

The invention consists, essentially, in first subjecting a mixture ofTiOZ-containing ore with-carbon to prolonged heating between 400 C. andl300 C., in maintaining it thereafter for a short period of time at ahigher temperature, comprised Vbetween l300 C. and 2500 C., and infinally maintaining it at a temperature comprised between l200 C. and2000 C. for a period of time sufficient for the separation of the formedcast iron.

The operations, according to the process of the invention, can becarried out in the presence of a flux, such as CaO, MgO, Si02, A1203,Na2O, etc.; and mixtures of these dilferent oxides. The temperatures andduration of the different steps of the above described operating cyclecan be varied, depending upon the nature of the flux employed and thedesired degree of concentration of the TiOz.

According to another feature of the invention, the heatingandparticularly the short-time heating to the highest temperatureispreferably carried out in the presence of a gas current flowing throughthe reaction mass; the effect of passing a gas at a high temperature isto promote the volatilization of impurities such as CaO, MgO, A1203,i02, etc., thus enabling a purer product to be obtained.

The temperatures most frequently used in the application of the newprocess are:V V600 to l200 C. during the initial heating periodoflongest duration, l800 to 2200 C. during the short-time (quick)heating, and l300 to 1800 C. during the final periodV during which theseparationof the slag from the cast iron takes place.

Patented Sept. 9, 1958 Depending upon the temperatures chosen for theoperation, the respective durations of the three heating periods canvary, but they are generally comprised between l and 8 hours for thefirst of these periods, between'lO and 45 minutes for the second, andfrom 30 minutes to 2 hours for the third period.

The process of the invention gives particularly attractive results whenusing a iiux having as essential components alkali compounds such as,for example, NazO, Na2CO3, etc. Under these conditions, it is possibleto operate at temperatures close to the lower limits of those set forthabove and the titanium oxide, separated as a liquid slag, can beobtained free of lime or magnesia admixtures (additions); this isparticularly advantageous when the manufactured product is intended forthe production of titanium chloride, since alkaline-earth compounds aredetrimental in the chlorination of titanium oxide.

Another advantage of the process of the invention resides in that itbecomes possible to liquefy the titaneferous slag by means of slightproportions of an alkali flux; these proportions can be far lower thanthose which would be required for transforming the titanium oxidepresent into alkali titanate.

Various apparatus can be employed for carrying out the describedprocess. For example, according to one embodiment of the invention, theheating of a mixture of ilmenite and coke or coal is carried out in arotating furnace adapted to provide the sequence of temperatures abovespecified. The operation can be carried out without liux, and there isthen, recoveredat the furnace outlet-on the one hand cast iron and, onthe other hand, a solid or pasty slag enriched in titanium oxide. Bysuitably controlling the ratio of carbon in the initial mixture, eitherthe iron oxides alone are reduced, or else the TiOz of the ore is alsopartially reduced. With a larger ratio of carbon, not only can TiO2 bereduced to titanium sub-oxides, but titanium carbide can be obtained inaddition; under these circumstances, the slag separated from the castiron leaving the furnace can be entirely solid and even pulverulent.

A rotating furnace can likewise be employed for working with fluxes, inwhich case liquid cast iron and slag are obtained at the furnace outlet,the temperatures being so controlled that the slag leaves the furnace inthe liquid state.

Remarkable results have been obtained by carrying out the new process ina shaft furnace. More particularly, a slag containing TiOz has beenobtained starting from ilmenites containing 33.4% FeO and about 55%Ti02. in fact, by carrying out the new process in a shaft furnace of thelow-stack-blast-furnace type blown with air enriched in oxygen, thereare obtained numerous advantages, the principal of which are: obtainmentof very high temperatures with a rather short zone making possible thevolatilization of impurities, very rapid reduction in this restrictedzone of high temperatures due to the direct action of solid carbon, andthe possibility of using alkali fluxes which, in the case of electricfurnaces, have known disadvantages. Another advantage resides in thehigh thermal eiiiciency by reason of the recovery of the produced gases.

ln order to illustrate the invention, there is described by Way ofexample only', and without limitation, an ernbodiment of the new processas carried out in a shaft furnace of the low-stack-blast-furnace type.The annexed single figure illustrates a partial, vertical section ofsuch a furnace.

The furnace used in carrying out the operation cornprise/.l a shaft 1ihaving a height of 4 m. and a diameter vof 1.16 m. at its belly 3; thedepth of the Crucible 4 measured between the plane of the tuyeres 2 andthe Percent T102 55 to 57 FeO to 33.4 A1203 1 to 3 SiOz. 1 to 2 CaO 0.5to 1 This ore, in the form of a very line black sand, was briquettedinto balls with 5% of a binder formed of pitch and manioc. Themetallurgical coke used contained ash. The sodium carbonate wasincorporated either into the balls themselves-thereby increasing theircohesionor else was charged in bulk directly into the furnace.

The hourly output of the furnace was 400. kg. titaneferons slag and 200kg. cast iron.

In the course of production, the temperature-measured within the shaft 3metres above the tuyere zonewas 200 to 400 C.; it varied between 800 and1200 C. at 1 metre above the tuyeres. At the level of the tuyeres, itwas 2000 to 2500 C. Decantation in the Crucible was effected between1600 and 1800o C. The material remained 3 to 5 hours within the shaftand 15 to 30 rninutes in the hot tuyere zone; the two liquid phasesremained 30 minutes to 1 hour in they Crucible before being run olf. Y

The titaneferous slag thus produced contained about 80% T102, and thiscontent reached 90% after eliminating the soda-containing ux by washingwith pure or slightly acid warm water. By way of example, there wasobtained a product having the following composition:

Percent MgO Traces Undetermined 0.5

The gas, recovered in the amount of 2.5 toV 3.5 m per kilogram of slag,had a caloriiic power of 1200 to 1400 cal/m9.

As regards the separated cast iron, it contained about 3% Si and 0.5 to1% Ti.

It is well understoodY that the carbon can be introduced in to thereaction mixture in the form of gas-coke, anthracite, wood charcoal,etc. rlhe alkali flux canbe in the form of another sait of sodium orpotassium, such as chloride, silicate, etc.

I claim:

l. Improvement in the process for treating titaniferous ore containingoxides of titanium and of iron to increase the titanium oxide contentthereof, wherein the iron oxides are reduced with carbonaceous materialto form cast iron and a slag enrichedvin titanium oxide, comprising the.following steps: subjecting a mixture of the ore and carbonaceousmaterial to prolonged heating within the range of 400 to 1300 C.;thereafter subjecting the heated mixture for a brief period of about 10to 45 minutes to further heating within the range of 18002500 C. and,iinally, heating the mixture within the range of 1300 to less than 1800C. to cause separation of cast iron and titanium oxide enriched slag,and thereafter recovering the enriched slag.

2. Process according to claim 1, wherein the ore con- 4 tains impuritiesother than those of iron, and a carrier gas current is passed throughthe heated mixture to promote volatilization of said impurities.

3. Process according to claim 1, wherein the mixture is blown withoxygen-enriched air.

4. Process according to claim 1, wherein the heating is carried,v out inthe presence of a ux.

5. Process according to claim 1 wherein the heating is carried out inthe presence of a flux containing an alkali metal.

6. Process according to claim 1, wherein the ratio of carbonaceousmaterial present in the initial mixture is sullcient to reduce the ironoxides only.

7. Process according to claim 1, wherein the ratio of carbonaceousmaterial present in the initial mixture is sufficient to reduce theiron, oxides and, at least partially reduce the titanium oxide.

8. P-rocess according to, claim 1, wherein the ratio of carbonaceousmaterial present` in the initial mixture is suicient to reduce theironand titanium oxides and form titanium carbide.

9. Process according to claim 1, wherein the slag is separated ina uidstate from the liquid cast iron.

10. Process-according to claim 8, wherein the slag is separated in asolid state-from the liquid cast iron.

11. Process according to claim 1, characterized in that the heating iscarried out in a low-stack-blast-furnace comprising a shaft, a bellysection, tuyeres and a crucible, and which furnace is blown withoxygen-enriched air, and further characterized in; that the prolongedheating of the mixture takes place in` the/shaft for a period of 3 to 5hours, the brief heating takes place in the belly section for a periodof 15 to 30 minutes, and the final heating takes place in the cruciblefor a` period of 30 minutes to 2 hours.

12. Process for treating a mixture` containing oxides of titanium andiron comprising the following steps: adding a carbonaceous reducingagent to said mixture, and passing the resultant massV through a furnacewherein the mass is subjectedv to, a heating cycle comprisingsuccessively, anl initial progressive` heating for a period of 3 to 5hours to 1300 C., a briefL heating to temperatures within the range` of18009-2200" C. for a period of 15 to 45 minutes,'and a nal heating to atemperature within the range of 1300 to less than 1800 C. for a periodof 30 minutes to 2 hours,\thereby forming separate layers of cast ironandslagtenriched intitanium oxide, and thereafter recovering said slag.

13. Process, for treating a mixture containing oxides of titanium andiron in a,low-stack-blast-furnace comprising a` shaft, belly section,tuyeres, and a Crucible, and blown with oxygen-enriched air, comprisingthe following steps: adding arcarbonaceous reducing agent to saidmixture, and passing the resultant mass through the furnace andsubjecting it to a heating cycle comprising successively, an initialheating in the shaft to temperatures within the, range of 400? to 1200C. for a period of 3 to 5 hours,V a brief heating to temperatures withinthe range of 20002500 C. forV a period of 15 to 30 minutes in the bellysection, and a final heating in the Crucible to a temperature within therange of 1600-1800 C. for a periodY of 30 minutes to 1 hour, therebyforming separate layers of cast iron and slag enriched in titanium oxideand, thereafter, recovering said slag.

References Cited inthe le of this patent UNITEDA STATESPATENTS 995,576Sinding-Larsen June 20, 1911 1,106,408 Rossiet al. Aug. 11, 19142,417,101 Campbell Mar. 11, 1947 2,445,377 Wyckoff July 21, 19482,537,229 McLaren Jan. 9, 1951 2,631,941 ColeV Mar. 17, 1953 2,680,681YArniant et al. June 8, 1954

1. IMPROVEMENT IN THE PROCESS FOR TREATING TITANIFEROUS ORE CONTAININGOXIDES OF TITANIUM AND OF IRON TO INCREASE THE TITANIUM OXIDE CONTENTTHEREOF, WHEREIN THE IRON OXIDES ARE REDUCED WITH CARBONACEOUS MATERIALTO FORM CAST IRON AND A SLAG ENRICHED IN TITANIUM OXIDE, COMPRISING THEFOLLOWING STEPS: SUBJECTING A MIXTURE OF THE ORE AND CARBONACEOUSMATERIAL TO PROLONGED HEATING WITHIN THE RANGE OF 400* TO 1300*C.;THEREAFTER SUBJECTING THE HEATED MIXTURE FOR A BRIED PERIOD OF ABOUT 10TO 45 MINUTES TO FURTHER HEATING WITHIN THE RANGE OF 1800*-2500* C. AND,FINALLY, HEATING THE MIXTURE WITHIN THE RANGE OF 1300* TO LESS THAN1800*C. TO CAUSE SEPARATION OF CAST IRON AND TITANIUM OXIDE ENRICHEDSLAG, AND THEREAFTER RECOVERING THE ENRICHED SLAG.